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Lebel, C.

Publications and source records attributed to Lebel, C..

At least 19 recordsLinked to original sources

The Canadian Pediatric Imaging Platform (C-PIP) Reference Sample: Neuroimaging Protocol and Cross-site Validation for Harmonized Multimodal Pediatric Imaging

Understanding how the human brain matures from infancy through adolescence is essential for identifying factors that influence health outcomes. Magnetic resonance imaging (MRI) provides powerful tools for characterizing structural, microstructural, functional, and metabolic aspects of brain development; however, many pediatric imaging studies are constrained by small sample sizes, limited geographic diversity, lack of longitudinal measurement, restricted age ranges, and heterogeneous acquisition protocols. While recent large-scale neuroimaging consortia have begun to address these challenges, such resources remain limited in the Canadian context, creating a critical gap. The Canadian Pediatric Imaging Platform (C-PIP) has developed a multisite neuroimaging framework across three of Canada's largest pediatric hospitals: Alberta Children's Hospital (Calgary), Centre Hospitalier Universitaire Sainte-Justine (Montreal), and the Hospital for Sick Children (Toronto). These three sites were united through a national initiative, leveraging high-performance MRI systems to accelerate Canadian neurodevelopmental research. In addition, C-PIP has implemented a centralized data sharing infrastructure to facilitate open science and collaborative research across institutions. Here, we describe the development and implementation of a multimodal MRI acquisition protocol designed to support multimodal longitudinal studies of typical and atypical brain development spanning infancy through adolescence. Within-site stability and cross-site stability of C-PIP core MRI sequences were evaluated using a travelling-participant study. The C-PIP MRI protocol establishes a harmonized, multisite imaging framework that supports large-scale investigations of pediatric brain development and disorders.

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Spatiotemporal Variation in White-Matter Development Across Early Childhood

Early childhood development is scaffolded by rapid maturation of brain white matter structure, believed to support the emergence of cognitive and socioemotional functions. Previous whole-tract studies have suggested patterns of white matter development occurring along posterior-anterior, deep-superficial and inferior-superior axes. However, little is known as to whether these patterns are evident within tracts. Using longitudinal diffusion imaging data from 133 children (4-8 years; 76 females), the present work characterizes along-tract patterns of white matter development across association, commissural and projection bundles using fixel-based analyses of microstructure and macrostructure. Within long range association bundles, faster age-related changes were observed for segments adjacent to the visual cortices relative to segments located near association regions, supporting a sensorimotor-association axis of brain development. An inferior-superior pattern was found for projection tracts, with faster age-effects observed for segments near the brainstem. Lastly, while several association and commissural bundles exhibited faster maturation within central segments; indicative of a deep-superficial axis, effects were mixed between micro- and macrostructure, underscoring the unique developmental timing of these different fiber properties. Our findings provide evidence that within-tract white matter maturation unfolds along key spatiotemporal axes and suggests that increased spatial precision can advance our understanding of early childhood brain development.

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Longitudinal Associations Between Screen Time, Brain Development, and Language Outcomes in Early Childhood

Language development during toddlerhood is supported by both neurobiological maturation and environmental experiences. It relies on reciprocal interaction, and excessive screen time exposure may have a negative impact. In the current study, we investigated how screen time at age two relates to language outcomes and brain development at ages two and three. Seventy toddlers underwent MRI scanning and neurodevelopmental testing, and brain volumes in language-related areas were extracted. Structural equation modelling showed that at age two, there was a negative relationship between screen time and pars triangularis volumes. Importantly, smaller volumes at age two predicted greater screen time usage at age three, mediated by poorer language outcomes. These results suggest that over time, children with smaller volumes and weaker language skills at age 2 became more likely to rely on screens at age 3, suggesting that early vulnerabilities amplify later screen use, highlighting the sensitivity of language networks to environmental input and the potential for screen exposure to alter developmental trajectories.

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Phonological decoding ability is associated with fiber density of the left arcuate fasciculus longitudinally across reading development

Numerous studies have linked reading ability to white matter microstructure using diffusion tensor imaging, but recent large studies have failed to show consistency. Fiber-specific diffusion-weighted magnetic resonance imaging (dMRI) models offer enhanced precision to measure specific features of white matter structure and may be more sensitive to individual differences in reading skills. However, fiber-specific models have not yet been applied to examine associations between reading ability and white matter microstructure over the course of reading acquisition. In this accelerated longitudinal study, we applied constrained spherical deconvolution (CSD) and fiber-specific modelling to characterize developmental changes in fiber density of key white matter tracts of the reading network bilaterally, and investigated associations between tract-wise fiber density and childrens phonological decoding abilities. Fiber density was measured from ages 2-13 years, and decoding ability (pseudoword reading) was assessed at ages 6 years and older. Higher decoding ability was associated with greater fiber density in the left arcuate fasciculus, and effects remained consistent over time. Follow-up analysis revealed that asymmetry changes in the arcuate fasciculus were moderated by decoding ability: good decoders showed leftward asymmetry from early childhood onward, while poorer decoders shifted toward leftward asymmetry over time. These results suggest that densely organized fibers in the left arcuate fasciculus serve as a foundation for the development of reading skills from the pre-reading stage through fluent reading. Ongoing developmental changes in fiber density and microstructural asymmetry throughout childhood may reflect a reciprocal relationship in which reading experience continues to refine and strengthen these pathways.

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Altered markers of brain metabolism and excitability are associated with executive functioning in young children exposed to alcohol in utero

Prenatal alcohol exposure (PAE) is the leading known cause of birth defects and cognitive disabilities, with impacts on brain development and executive functioning. Abnormalities in structural and functional brain features are well-documented in children with PAE, but the effects of PAE on brain metabolism in children have received less attention. Levels of brain metabolites can be measured non-invasively using magnetic resonance spectroscopy (MRS). Here, we present the first study of PAE-related brain metabolite differences in early childhood (ages 3-8 years) and their associations with cognitive performance, including executive functioning (EF) and pre-reading skills. We measured metabolites in two cohorts of children with PAE and unexposed children using MRS in the anterior cingulate cortex (ACC; cohort 1) and left temporo-parietal cortex (LTP; cohort 2). Total choline (tCho), a marker of membrane/myelin metabolism, was elevated in both regions in children with PAE compared to unexposed children, and glutamate+glutamine (Glx), a marker of excitability, was elevated in the ACC. The PAE group exhibited more difficulties with EF, and higher tCho was associated with better EF in both PAE and unexposed groups. In addition, elevated Glx in the ACC was associated with poorer inhibitory control within the PAE group only. LTP metabolites were not significantly associated with pre-reading skills in PAE or unexposed groups. Together, these findings point to altered membrane metabolism and excitability in young children with PAE. These findings provide new insight to potential mechanisms by which PAE disrupts brain development and cognitive functioning in early childhood.

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White matter tract microstructure, macrostructure, and associated cortical gray matter morphology across the lifespan

Characterizing how, when and where the human brain changes across the lifespan is fundamental to our understanding of developmental processes of childhood and adolescence, degenerative processes of aging, and divergence from normal patterns in disease and disorders. We aimed to provide detailed descriptions of white matter pathways across the lifespan by thoroughly characterizing white matter microstructure, white matter macrostructure, and morphology of the cortex associated with white matter pathways. We analyzed 4 large, high-quality, publicly-available datasets comprising 2789 total imaging sessions, and participants ranging from 0 to 100 years old, using advanced tractography and diffusion modeling. We first find that all microstructural, macrostructural, and cortical features of white matter bundles show unique lifespan trajectories, with rates and timing of development and degradation that vary across pathways - describing differences between types of pathways and locations in the brain, and developmental milestones of maturation of each feature. Second, we show cross-sectional relationships between different features that may help elucidate biological changes occurring during different stages of the lifespan. Third, we show unique trajectories of age-associations across features. Finally, we find that age associations during development are strongly related to those during aging. Overall, this study reports normative data for several features of white matter pathways of the human brain that will be useful for studying normal and abnormal white matter development and degeneration.

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Changes in brain metabolite levels across childhood

Metabolites play important roles in brain development and their levels change rapidly in the prenatal period and during infancy. Metabolite levels are thought to stabilize during childhood, but the development of neurochemistry across early-middle childhood remains understudied. We examined the developmental changes of key metabolites (total N-acetylaspartate, tNAA; total choline, tCho; total creatine, tCr; glutamate+glutamine, Glx; and myo-inositol, mI) using short echo-time magnetic resonance spectroscopy (MRS) in the anterior cingulate cortex (ACC) and the left temporo-parietal cortex (LTP) using a mixed cross-sectional/longitudinal design in children aged 2-11 years (ACC: N=101 children, 112 observations; LTP: N=95 children, 318 observations). We found age-related effects for all metabolites. tNAA increased with age in both regions, while tCho decreased with age in both regions. tCr increased with age in the LTP only, and mI decreased with age in the ACC only. Glx did not show linear age effects in either region, but a follow-up analysis in only participants with [≥]3 datapoints in the LTP revealed a quadratic effect of age following an inverted U-shape. These substantial changes in neurochemistry throughout childhood likely underlie various processes of structural and functional brain development.

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Hypothalamic vasopressin sex differentiation is established during embryonic neurogenesis

Arginine vasopressin (AVP) is a conserved sexually dimorphic system regulating behaviors and physiologies. Decades of research concludes that AVP sex differentiation in mice occurs around birth when a gonadal surge of testosterone is converted to estrogen in male sexual dimorphic brain regions. We discovered that AVP neurons in the murine hypothalamus are sexually dimorphic much earlier than this surge, with male mice displaying more AVP neurons than females during neurogenesis at E11. In utero exposure to a pan-ER antagonist blocked AVP masculinization in males, whereas embryonic exogenous 17{beta}-estradiol or xenoestrogen bisphenol A (BPA) masculinized female AVP neurons, causing permanent masculinization effects on adult female AVP cell numbers, projections and intrinsic neuronal properties. Our data reveal that sexual dimorphism of hypothalamic AVP neurons is present from the earliest stages of their differentiation and challenges current dogma that masculinization of the male brain occurs around birth. One-Sentence SummarySexual dimorphism of hypothalamic vasopressin is established during neurogenesis and exposure to the xenoestrogen bisphenol A during pregnancy induces masculinization of female brains

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Multimodal brain features at preschool age and the relationship with pre-reading measures one year later: an exploratory study

Pre-reading language skills develop rapidly in early childhood and are related to brain structure and function in young children prior to formal education. However, the early neurobiological development that support these skills is not well understood and has not been assessed longitudinally using multiple imaging approaches. Here we acquired anatomical, diffusion tensor imaging (DTI) and resting state functional MRI (rs-fMRI) from 35 children at 3.5 years of age. Children were assessed for pre-reading abilities using the NEPSY-II subtests one year later (4.5 years). We applied a data-driven linked independent component analysis to explore the shared co-variation of grey and white matter measures. Two sources of structural variation at 3.5 years of age demonstrated a weak relationship with Speeded Naming scores at 4.5 years of age. The first imaging component involved volumetric variability in reading-related cortical regions alongside microstructural features of the superior longitudinal fasciculus. The second component was dominated by cortical volumetric variations within the cerebellum and visual association area. In a subset of children with rs-fMRI data, we evaluated the inter-network functional connectivity of the left-lateralized fronto-parietal language (FPL) network and its relationship with pre-reading measures. Higher functional connectivity between the FPL functional network and the default mode and visual networks at 3.5 years predicted better Phonological Processing scores at 4.5 years. Together, these results suggest that the integration of functional networks, as well as the co-development of white and grey matter brain structures in early childhood, may support the emergence of pre-reading measures in preschool children.

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Association between breastfeeding during infancy and white matter microstructure in early childhood

IntroductionAssociations between breastfeeding and brain development, in the context of child, perinatal, and sociodemographic variables, remain unclear. This study investigates whether exclusive breastfeeding for the first 6 months and total duration of any breastfeeding are associated with brain white matter microstructure in young children. MethodsThis study included a sample of 83 mothers and 85 typically developing children (42 males). Children underwent their first diffusion tensor imaging scan between ages 2.34-6.97 years; some children returned multiple times, providing a total of 331 datasets. Feeding information was collected from the mothers at 3, 6, and 12 months postpartum and at their childs scan to calculate breastfeeding status at 6 months (exclusive or not) as well as total duration of any breastfeeding. Linear regression was used to investigate associations between breastfeeding exclusivity/duration and fractional anisotropy (FA, a measure sensitive to myelination/axonal packing/fibre coherence) for the whole brain and 10 individual white matter tracts. ResultsBreastfeeding exclusivity and duration were associated with global and regional white matter microstructure, even after controlling for perinatal and sociodemographic factors. Greater exclusivity was associated with higher FA in females and lower FA in males. ConclusionsThese findings suggest white matter differences associated with breastfeeding that differ by sex. These may stem from different trajectories in white matter development between males and females in early childhood and suggest possible long-term white matter differences associated with breastfeeding.

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White Matter Alterations in Young Children with Prenatal Alcohol Exposure

Prenatal alcohol exposure (PAE) can lead to cognitive, behavioural, and social-emotional challenges. Previous neuroimaging research has identified alterations to brain structure in newborns, older children, adolescents, and adults with PAE; however, little is known about brain structure in young children. Extensive brain development takes place during early childhood; therefore, understanding the neurological profiles of young children with PAE is critical for early identification and effective intervention. We studied 54 children (5.21{+/-}1.11 years; 27 males) with confirmed PAE compared to 54 age- and sex-matched children without PAE. Children underwent diffusion tensor imaging between 2 and 7 years of age. Mean fractional anisotropy (FA) and mean diffusivity (MD) were obtained for 10 major white matter tracts, along with tract volume, axial and radial diffusivity (AD, RD). A univariate analysis of covariance was conducted to test for group differences (PAE vs. control) controlling for age, sex and tract volume. Our results reveal white matter microstructural differences between young children with PAE and unexposed controls. The PAE group had higher FA and/or lower MD (as well as lower AD and RD) in the genu and the body of the corpus callosum, as well as the bilateral uncinate fasciculus and pyramidal tracts. Our findings align with studies of newborns with PAE finding lower AD, but contrast those in older populations with PAE, which consistently report lower FA and higher MD. These findings may reflect premature development of white matter that may then plateau too early, leading to the lower FA/higher MD observed at older ages.

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Multimodal principal component analysis to identify major features of white matter structure and links to reading

The role of white matter fibers in reading has been established by diffusion tensor imaging (DTI), but DTI cannot identify specific microstructural features driving these relationships. Neurite orientation dispersion and density imaging (NODDI), inhomogeneous magnetization transfer (ihMT) and multicomponent driven equilibrium single-pulse observation of T1/T2 (mcDESPOT) can be used to link more specific aspects of white matter microstructure and reading due to their sensitivity to axonal packing and fiber coherence (NODDI) and myelin (ihMT and mcDESPOT). We applied principal component analysis (PCA) to combine DTI, NODDI, ihMT and mcDESPOT measures (10 in total), identify major features of white matter structure, and link these features to both reading and age. Analysis was performed for nine reading-related tracts in 46 neurotypical 6-16 year olds. We identified three principal components (PCs) which explained 79.5% of variance in our dataset. PC1 probed tissue complexity, PC2 described myelin and axonal packing, while PC3 was related to axonal diameter. Mixed effects models regressions did not identify any relationships between principal components and reading skill. Further Bayes factor analysis revealed that absence of relationships was not due to low power. PC1 suggested increases in tissue complexity with age in the left arcuate fasciculus, while PC2 suggested increases in myelin and axonal packing with age in the bilateral arcuate, inferior longitudinal, inferior fronto-occipital fasciculi, and splenium. Multimodal white matter imaging and PCA produce microstructurally informative, powerful principal components which can be used by future studies of development and cognition.

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Maturation and interhemispheric asymmetry in neurite density and orientation dispersion in early childhood

BackgroundThe brains white matter undergoes profound changes during early childhood, which are believed to underlie the rapid development of cognitive and behavioral skills during this period. Neurite density, and complexity of axonal projections, have been shown to change across the life span, though changes during early childhood are poorly characterized. Here, we utilize neurite orientation dispersion and density imaging (NODDI) to investigate maturational changes in tract-wise neurite density index (NDI) and orientation dispersion index (ODI) during early childhood. Additionally, we assess hemispheric asymmetry of tract-wise NDI and ODI values, and longitudinal changes. MethodsTwo sets of diffusion weighted images (DWI) with different diffusion-weighting were collected from 125 typically developing children scanned at baseline (N=125; age range=4.14-7.29; F/M=73/52), 6-month (N=8; F/M=8/0), and 12-month (N=52; F/M=39/13) timepoints. NODDI and template-based tractography using constrained spherical deconvolution were utilized to calculate NDI and ODI values for major white matter tracts. Mixed-effects models controlling for sex, handedness, and in-scanner head motion were utilized to assess developmental changes in tract-wise NDI and ODI. Paired t-tests were used to assess interhemispheric differences in tract-wise NDI and ODI values and longitudinal changes in cross-sectional and 12-month longitudinal analyses, respectively. ResultsMaturational increases in NDI were seen in all major white matter tracts, though we did not observe the expected tract-wise pattern of maturational rates (e.g. fast commissural/projection and slow frontal/temporal tract change). ODI did not change significantly with age in any tract. We observed higher cross-sectional NDI and ODI values in the right as compared to the left hemisphere for most tracts, but no hemispheric asymmetry for longitudinal changes. ConclusionsThese findings suggest that neurite density, but not orientation dispersion, increases with age during early childhood. In relation to NDI growth trends reported in infancy and late-childhood, our results suggest that early childhood may be a transitional period for neurite density maturation wherein commissural/projection fibers are approaching maturity, maturation in long range association fibers is increasing, and changes in limbic/frontal fibers remain modest. Rightward asymmetry in NDI and ODI values, but not longitudinal changes, suggests that rightward asymmetry of neurite density and orientation dispersion is established prior to age 4.

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Examining the relationship between prenatal depression, amygdala-prefrontal structural connectivity and behaviour in preschool children

Prenatal depression is a common, underrecognized, and undertreated condition with negative consequences on child behaviour and brain development. Neurological dysfunction of the amygdala, cingulate cortex and hippocampus are associated with the development of depression and stress disorders in youth and adults. Although prenatal depression is associated with both child behaviour and neurological dysfunction, the relationship between these variables remains unclear. In this study, fifty-four mothers completed the Edinburgh Depression Scale (EDS) during the second and third trimester of pregnancy and 3 months postpartum. Their childrens behaviour was assessed using the Child Behaviour Checklist (CBCL), and the children had diffusion magnetic resonance imaging (MRI) at age 4.1 +/- 0.8 years. Associations between prenatal depressive symptoms, child behaviour, and child brain structure were investigated. Third trimester EDS scores were associated with altered white matter in the amygdala-frontal tract and the cingulum, controlling for postpartum depression. Externalizing behaviour was sexually differentiated in the amygdala-frontal pathway. Altered structural connectivity between the amygdala and frontal cortex mediated the relationship between third trimester maternal depressive symptoms and child externalizing behaviour in males, but not females. These findings suggest that altered brain structure is a possible mechanism via which prenatal depressive symptoms can impact child behaviour, highlighting the importance of both recognition and intervention in prenatal depression.

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Early childhood development of white matter fiber density and morphology

Early childhood is an important period for cognitive and brain development, though white matter changes specific to this period remain understudied. Here we utilize a novel analytic approach to quantify and track developmental changes in white matter micro- and macro-structure, calculated from individually oriented fiber-bundle populations, termed \"fixels\". Fixel-based analysis and mixed-effects models were used to assess tract-wise changes in fiber density and bundle morphology in 73 girls scanned at baseline (ages 4.09-7.02, mean=5.47, SD=0.81), 6-month (N=7), and one-year follow-up (N=42). For comparison, we also assessed changes in commonly utilized diffusion tensor metrics: fractional anisotropy (FA), and mean, radial and axial diffusivity (MD, RD, AD). Maturational increases in fixel-metrics were seen in most major white matter tracts, with the most rapid increases in the corticospinal tract and slowest or non-significant increases in the genu of the corpus callosum and uncinate fasciculi. As expected, we observed developmental increases in FA and decreases in MD, RD and AD, though percentage changes were smaller relative to fixel-metrics. The majority of tracts showed more substantial morphological than microstructural changes. These findings highlight early childhood as a period of dynamic white matter maturation, characterized by large increases in macroscopic fiber bundle size, mild changes in axonal density, and parallel, albeit less substantial, changes in diffusion tensor metrics.

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Cerebral Blood Flow Increases Across Early Childhood

Adequate cerebral blood flow (CBF) is essential to proper brain development and function. Detailed characterization of CBF developmental trajectories will lead to better understanding of the development of cognitive, motor, and sensory functions, as well as behaviour in children. Previous studies have shown CBF increases during infancy and decreases during adolescence; however, the trajectories during childhood, and in particular the timing of peak CBF, remain unclear. Here, we used arterial spin labeling to map age-related changes of CBF across a large longitudinal sample that included 279 scans on 96 participants (46 girls and 50 boys) aged 2-7 years. CBF maps were analyzed using hierarchical linear regression for every voxel inside the grey matter mask, controlling for multiple comparisons. The results revealed a significant positive linear association between CBF and age in distributed brain regions including prefrontal, temporal, parietal, and occipital cortex, and in the cerebellum. There were no differences in developmental trajectories between males and females. Our findings suggest that CBF continues to increase at least until the age of 7 years, likely supporting the ongoing improvements in behaviour, cognition, motor, and sensory functions of the children in early childhood.\n\nHighlights* We mapped cerebral blood flow development longitudinally in 96 typically developing children aged 2-7 years\n* Cerebral blood flow increased over the full age range\n* No significant differences between males and females were found\n\n\nConflicting of InterestR.M.L. is an employee of GE.

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Global and regional white matter development in early childhood

White matter development continues throughout childhood and into early adulthood, but few studies have examined early childhood, and the specific trajectories and regional variation in this age range remain unclear. The aim of this study was to characterize developmental trajectories and sex differences of white matter in typically developing young children. Three hundred and ninety-six diffusion tensor imaging datasets from 120 children (57 male) aged 2-8 years were analyzed using tractography. Fractional anisotropy (FA) increased and mean diffusivity (MD) decreased in all white matter tracts by 5-15% over the 6-year period, likely reflecting increases in myelination and axonal packing. Males showed steeper slopes in a number of brain areas. Overall, early childhood is associated with substantial development of all white matter and appears to be an important period for the development of occipital and limbic connections, which showed the largest changes. This study provides a detailed characterization of age-related white matter changes in early childhood, offering baseline data that can be used to understand cognitive and behavioural development, as well as to identify deviations from normal development in children with various diseases, disorders, or brain injuries.

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Tractography Reproducibility Challenge with Empirical Data (TraCED): The 2017 ISMRM Diffusion Study Group Challenge

PurposeFiber tracking with diffusion weighted magnetic resonance imaging has become an essential tool for estimating in vivo brain white matter architecture. Fiber tracking results are sensitive to the choice of processing method and tracking criteria. Phantom studies provide concrete quantitative comparisons of methods relative to absolute ground truths, yet do not capture variabilities because of in vivo physiological factors.\n\nMethodsTo date, a large-scale reproducibility analysis has not been performed for the assessment of the newest generation of tractography algorithms with in vivo data. Reproducibility does not assess the validity of a brain connection however it is still of critical importance because it describes the variability for an algorithm in group studies. The ISMRM 2017 TraCED challenge was created to fulfill the gap. The TraCED dataset consists of a single healthy volunteer scanned on two different scanners of the same manufacturer. The multi-shell acquisition included b-values of 1000, 2000 and 3000 s/mm2 with 20, 45 and 64 diffusion gradient directions per shell, respectively.\n\nResultsNine international groups submitted 46 tractography algorithm entries. The top five submissions had high ICC > 0.88. Reproducibility is high within these top 5 submissions when assessed across sessions or across scanners. However, it can be directly attributed to containment of smaller volume tracts in larger volume tracts. This holds true for the top five submissions where they are contained in a specific order. While most algorithms are contained in an ordering there are some outliers.\n\nConclusionThe different methods clearly result in fundamentally different tract structures at the more conservative specificity choices (i.e., volumetrically smaller tractograms). The data and challenge infrastructure remain available for continued analysis and provide a platform for comparison.

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